REPORT ON AN INVESTIGATION INTO THE CAUSE OF CRACKING OF THE BITUMINOUS SURFACING ON A PROVINCIAL ROAD NEAR VILJOENSDRIF, ORANGE FREE STATE

AN INVESTIGATION WAS CARRIED OUT INTO THE CAUSE OF CRACKING OF THE BITUMINOUS SURFACING ON A PROVINCIAL ROAD NEAR VILJOENSDRIF, ORANGE FREE STATE. IT WAS CONCLUDED THAT THE MAIN CAUSE OF THE PROBLEM WAS A SIGNIFICANT PYRITE CONTENT OF THE REEF QUARTZITE USED IN THE BASE WHICH GAVE RISE TO THE FORMATION OF SOLUBLE SALTS WHICH CRYSTALLIZED AT THE INTERFACE BETWEEN THE BASE AND THE SURFACING. WHERE DOUBT EXISTS CONCERNING THE POSSIBLE SALT-FORMING POTENTIAL OF A SOURCE OF ROCK, EXPERIENCE HAS SHOWN THAT THE FOLLOWING METHODS CAN BE ADOPTED: (1) LAYING A RELATIVELY IMPERMEABLE SURFACING AS SOON AS THE BASE IS JUST DRY ENOUGH TO WORK ON BUT WITHOUT LETTING IT DRY OUT COMPLETELY, AND (2) LEAVING THE PRIMED BASE UNSURFACED FOR, SAY, TWO TO FOUR MONTHS DURING WHICH THE BASE IS OPENED TO TRAFFIC. IF THE FORMATION OF SALTS DOES TAKE PLACE, IT IS LIKELY THAT MOST OF THE SALTS THAT ARE POTENTIALLY AVAILABLE WILL ACCUMULATE ON THE SURFACE DURING THIS PERIOD AND BE REMOVED PRIOR TO SURFACING. /ARTICLE/

  • Supplemental Notes:
    • Vol 10, No 1, P 5, RM/5/68
  • Publication Date: 0

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Filing Info

  • Accession Number: 00211458
  • Record Type: Publication
  • Source Agency: Nat Inst Road Research /S Africa
  • Files: TRIS
  • Created Date: Jan 12 1970 12:00AM